CAREER: The Role of Iron and Reactive Oxygen Species in the Oxidation and Fate of DOM in Natural Waters

这项研究将确定铁在涉及DOM降解的光反应和暗反应中的直接和间接作用，并估计铁在确定这种降解是将C沿河流分流到海洋中，还是将C完全氧化为释放到大气中的CO2的重要性。这项拟议的工作将促进我们对地表扰动期间暴露在氧气或阳光下的地球表面土壤碳的退化的理解。这一知识将使科学家能够更好地预测北极永久冻土中碳的命运，并通过教育和推广计划，使社会能够通过北极融化的积极反馈，更好地为全球变暖的潜在加速做准备。为了让代表不足的学生参与科学，国际学生联合会建议通过伙伴关系扩大教育基础设施，这将为提高教学和沟通技能提供新的机会。国际地球科学协会将开发一门与她的研究相结合的地球和环境科学课程，以核心教育原则为基础，并根据评估目标进行规划。对课程开发的一项新贡献将是(1)教育模块的组合？望远镜？在从K-12到本科生再到成人的年龄背景和难度方面，(2)通过对成绩的微观评估生成关于学生参与和学习的数据，以及(3)通过反复改进学生为自己的同龄人群体提供的单元来加强主动学习。这项研究将在阿拉斯加北极地区进行，因为(1)湖泊、溪流和土壤水提供了光、氧、DOM和铁浓度的自然实验矩阵，以及(2)冻土中有大量的有机碳(至少是目前大气中碳含量的两倍)，正因全球变暖而迅速融化。通过对天然水域的实地调查和实验来检验机理假说，PI将回答两个主要的研究问题：(1)铁介导的反应是否有利于DOM在阳光和微生物的作用下完全氧化成CO2？(2)铁在黑暗中对DOM的氧化是DOM命运的重要决定因素吗？

Title: The role of iron and reactive oxygen species in the oxidation and fate of DOM in natural waters This study will determine the direct and indirect roles of iron in both light and dark reactions involving DOM degradation, and estimate the importance of iron in determining whether this degradation will shunt C as DOM down rivers to oceans, or fully oxidize C to CO2 released to the atmosphere. The proposed work will advance our understanding of the degradation of soil carbon exposed to oxygen or sunlight at Earth?s surface during land-surface disturbances. This knowledge will allow scientists to better predict the fate of C in arctic permafrost soils, and through an education and outreach plan, will allow society to better prepare for the potential acceleration of global warming through a positive feedback from the thawing Arctic. To engage underrepresented students in science, the PI proposes to expand the infrastructure of education through partnerships that will offer new opportunities to enhance teaching and communication skills. The PI will develop a curriculum in earth and environmental science integrated with her research, grounded in core education principles, and mapped to assessment goals. A novel contribution to curriculum development will be the combination of (1) education modules that ?telescope? in age-context and difficulty from K-12 to undergraduate to adult outreach levels, (2) data generation on student engagement and learning through micro-assessments of performance, and (3) enhanced active learning by iterative improvement of modules by students for their own peer groups. This research will be done in the Alaskan Arctic because (1) the lakes, streams, and soil waters provide a natural experimental matrix of both high and low light, oxygen, DOM and Fe concentrations, and (2) there are tremendous stores of organic C in frozen soils (at least twice the amount of C now in the atmosphere) which are rapidly thawing from global warming. Using field surveys and experiments on natural waters to test mechanistic hypotheses, the PI will answer two main research questions: (1) Do reactions mediated by iron favor the complete oxidation of DOM to CO2 by sunlight and microbes? (2) Is the iron-mediated oxidation of DOM in the dark an important determinant of DOM fate?